In the aftermath of September 11, a host of federal agencies have come under intense scrutiny. The Federal Aviation Administration, the Federal Bureau of Investigation, and the Central Intelligence Agency have all been charged with responsibility for failures leading up to the attacks. In each case, the culture within the agency, as well as its mission, policies, and procedures, has been examined in a variety of public forums. The Immigration and Naturalization Service (INS) has also been excoriated for several spectacular gaffs - most infamously, for sending notification to a Florida flight school that two of the hijackers had been approved as students six months after their deaths. But there has been no comparable effort to examine the failures of our immigration system. For example, all of the September 11 hijackers were issued visas, but there have been no extensive congressional hearings or investigations by the General Accounting Office or the Office of the Inspector General to determine whether the State Department, which issued the visas, erred in any way.

Given the fact that the current terrorist threat to the United States comes primarily from foreign-born individuals, immigration services would seem to be an obvious area of inquiry. Of course, no immigration system can be completely foolproof, but it does not have to be. Even if only some of those individuals can be detained by our immigration system, it is possible that whatever conspiracy they are part of could be uncovered.

While they were the most destructive in American history, the attacks of last September were not the first carried out by foreign terrorists on U.S. soil. To gain a more complete picture of the threat and of the holes in our immigration system, we must examine acts of terrorism in this country over the last decade. Including the September 11 hijackers, 48 foreign-born militant Islamic terrorists have been charged, or convicted, or have admitted their involvement in terrorism within the United States between 1993 and 2001. In addition to September 11, the plots examined here include the murder of employees outside of CIA headquarters in 1993, the first attack on the World Trade Center in the same year, a plot to bomb the Brooklyn subway system in 1997, plots to bomb New York City landmarks in 1993, and the Millennium plot to bomb Los Angeles International Airport. Almost all of them have now been linked in some way to Osama bin Laden's al Qaeda organization. To be sure, other terrorist threats exist. However, because the threat it poses dwarfs that of any other terrorist group, foreign or domestic, the emphasis here will be on al Qaeda.

Entering Every Which Way

In the wake of September 11, some observers have emphasized the mismanagement of temporary visas, such as those issued to students and tourists, because all of the 19 hijackers were originally allowed into the country on temporary visas. Others have argued that there is a problem with illegal immigration, because at least three of the hijackers - four if Zacarias Moussaoui, who the U.S. government claims was the intended twentieth hijacker, is included - had overstayed their visas and were illegal aliens at the time of the attacks. But in fact the danger cannot be isolated to one type of immigration. Foreign-born Islamic terrorists have used almost every conceivable means of entering the country over the last decade. They have come as students, tourists, and business visitors. They have also been lawful permanent residents (LPRs) and naturalized U.S. citizens. They have sneaked across the border illegally, arrived as stowaways on ships, used false passports, or been granted amnesty. Terrorists have even exploited America's humanitarian tradition of welcoming those seeking asylum. At the time they committed their crimes, 16 of the 48 terrorists considered in this analysis were on temporary visas (primarily tourist visas); another 17 were lawful permanent residents or naturalized U.S. citizens; 12 were illegal aliens; and 3 of the 48 had applications for asylum pending.

Even some government officials have mistakenly singled out one type of immigration as the source of the problem. During testimony before the immigration subcommittee in the Senate shortly after the September attacks, INS commissioner James Ziglar stated, "Immigrants are not terrorists.... The people that we are talking about, the hijackers, they weren't immigrants. They were nonimmigrants." While it is certainly true that the September 11 hijackers entered the country using nonimmigrant visas (also called temporary visas), the commissioner is incorrect if his comments were meant to indicate that permanent residents are not a source of terrorism. In fact, prior to September 11, most foreign terrorists were LPRs or nationalized U.S. citizens. Excluding the hijackers, more than half (17 out of 28) of the foreign-born Islamic terrorists in the last decade were persons living legally in the United States as permanent residents or as naturalized citizens.

Indeed, some of the worst foreign terrorists have been naturalized citizens. For example, El Sayyid Nosair, who assassinated Rabbi Meir Kahane in 1990, was one of the first militant Islamic terrorists to strike in the United States. A naturalized U.S. citizen, he was later convicted as a member of the larger conspiracy to bomb landmarks around New York City. Nidal Ayyad, a chemical engineer who provided the explosive expertise for the first World Trade Center bombing in 1993, was also a naturalized U.S. citizen. So too were Egyptian-born Ali Mohammed, who is widely regarded as having written al Qaeda's terrorist handbook, and Khalid Abu al Dahab, who has been described as "a one-man communications hub" for shuttling money and fake passports to terrorists around the world from his California apartment.

Lawful permanent residents (also known as green-card holders) have also played an integral role in terrorism. In all, 11 LPRs have been convicted or pled guilty to terrorist activities. These include Mahmud Abouhalima, one of the leaders of the first World Trade Center bombing, who became a legal resident after falsely claiming to be an agricultural worker, allowing him to qualify for a green card as part of the 1986 amnesty. Another LPR was Mohammed Saleh, who provided the money and the fuel oil needed to create the bombs for the massive terrorist plot targeting landmarks around New York City in the summer of 1993. The ringleader of this plot, Siddig Ibrahim Siddig Ali, was also a legal permanent resident.

The nation's humanitarian tradition of offering refuge to those fleeing persecution has also been exploited by a number of terrorists. Three of them had asylum claims pending when they committed their crimes. Sheik Omar Abdel Rahman used an asylum application to prevent his deportation to Egypt after all other means of remaining in the country had failed. Rahman inspired both the first World Trade Center attack and the plot to bomb New York City landmarks. Moreover, he is widely considered to be one of the spiritual leaders whose ideas helped to found al Qaeda. Mir Aimal Kansi, who murdered two CIA employees in 1993, and Ramzi Yousef, who was sentenced to death for masterminding the first attack on the World Trade Center, both had applications for political asylum pending.

While most foreign-born terrorists were in the country legally, either as temporary visitors, lawful permanent residents, or naturalized citizens, illegal aliens have also taken part in almost every major terrorist attack on American soil, including the first attack on the World Trade Center, the Millennium plot, the plot to bomb the Brooklyn subway system, and the attacks of September 11. Of the 48 Islamic terrorists in the last decade, 12 were in the country illegally when they committed their crimes. (It may also be more accurate to include asylum applicants in the category of illegal aliens, because all of the three terrorists discussed above had no legal basis for being in the United States and were awaiting the outcome of the asylum process.) Altogether, 19 foreign terrorists over the last decade were either illegal aliens at the time they engaged in terrorism or had lived in the United States illegally for an extended period before they committed their crimes.

How did all these terrorists get into the country? The plain fact is that they exploited weaknesses in nearly every part of the U.S. immigration system, from its visa-processing operations overseas, to control of the border and ports of entry, to green-card issuance. An examination of these problems reveals inadequate vetting of visa applicants, lack of cooperation among U.S. agencies and between the United States and foreign governments, failure to adequately police the borders, and a complete lack of interior enforcement.

Eyes Wide Shut

In a very real sense, Foreign Service officers are America's other border patrol. It is they who determine, in most cases, who is allowed into the country. Of the 48 terrorists considered here, 41 had at some point been approved for a visa by an American consulate overseas. Though we cannot expect that in every case the visa-processing system will quickly identify the terrorist applicant and prevent him from getting a visa, the fact that so many terrorists made it through certainly suggests that there are significant problems in the system.

The primary tool used in flagging terrorists is called the "watch list" or "lookout" system. It is a compilation of several million people who are not to be issued visas or otherwise allowed to enter the country. Currently, the database is composed of names, dates of birth, countries, and passport numbers rather than biometric identifiers such as photographs or fingerprints. The names of persons applying for visas are checked against the list. In some cases, procedural failures and outdated technology have caused the system to fail.

Probably the most infamous person to be mistakenly issued a visa is Egypt-born Sheik Omar Abdel Rahman. Although on the watch list, Rahman was issued a tourist visa because consular employees in Khartoum, Sudan, did not properly check the list. Although most large corporations had computerized their databases by the mid 1980s, most consular offices were still using microfiche to store and search names on the watch list. This made it much more likely that a name could be missed. Similarly, Ali Mohammed was placed on the watch list in 1984 but was still able to get a visa from an American embassy in Cairo. The list was not automated at the time, and his extremely common name may account for the oversight. Mohammed eventually married an American and lived in the United States for many years, working for al Qaeda and helping to plan a number of attacks. Learning the names of al Qaeda terrorists is an enormous intelligence challenge, but in the cases of Sheik Rahman and Ali Mohammed, whose links to terrorism were known, the system should have kept them from entering the country.

However, not all problems were the result of INS or State Department failures. In a number of cases, it appears that U.S. intelligence agencies or foreign governments did not inform the INS or the State Department that an individual might be a security risk.

Mahmud Abouhalima and Zacarias Moussaoui were both known to U.S.-friendly governments as individuals with links to terrorism. As a teenager in Egypt, Mahmud Abouhalima became involved with the outlawed al-Jama'a Islamiyya, an Islamic extremist organization. He had been under surveillance by the Egyptian government, and a number of his associates were imprisoned prior to his 1981 departure for Germany. But because his name was not on the watch list, Abouhalima was granted a tourist visa in 1985 by an American consulate in Germany. Zacarias Moussaoui's circumstances were similar. Moussaoui was known as a possible terrorist to French authorities, but his name was not on the U.S. watch list. And because France is part of the visa waiver program, which allows people to enter the United States and stay for up to 90 days without a visa, Moussaoui, a French citizen, was able to enter the United States easily.

For years the State Department and the INS have complained that the intelligence agencies and FBI have not been entirely forthcoming with the names of suspected terrorists, partly because they fear sources might be compromised. The case of Khalid al Midhar, who may have piloted American Airlines Flight 77 into the Pentagon, demonstrates the importance of information sharing. Al Midhar's terrorist activities were not known to U.S. authorities when he received his business visa in Saudi Arabia in 1999 or when he entered the country for the first time in January 2000. In January 2001, while al Midhar was out of the country, the CIA became aware that he was involved in the attack on the USS Cole the year before. However, his name was not placed on the watch list until August 2001. Unfortunately, he had already re-entered the United States in July. The fact that it took the CIA several months to put al Midhar's name on the watch list indicates that, at the very least, the agency considered the list a low priority. It must be pointed out that al Midhar's visa allowed for multiple re-entries. However, if his name had been on the watch list, an INS inspector at the port of entry might have detained him.

Welcome to America

While failure to update or administer the watch list properly is clearly a serious weakness in the immigration system, the way visas are processed overseas presents an even larger problem. Before Assistant Secretary of State Mary Ryan was forced out of office last July, the Consular Service had adopted a culture of service rather than skepticism, one in which visa officers are expected to consider applicants as their customers. Satisfying the customer - the foreign visa applicant - has become one of the service's most important goals, leading to pressure to speed processing and approve marginal applications. As one former Foreign Service officer has written, "State Department procedures call for supervisory review of refusals, but not issuances - thus, relatively inexperienced junior officers are trusted to issue visas but are second-guessed on refusals." Visa officers are judged by the number of applications processed each day and by their politeness to applicants rather than on their thoroughness in screening applicants.

The case of Lafi Khalil, who was involved in the plot to bomb a Brooklyn subway station in 1997, illustrates a number of problems with the way interviews are conducted overseas. In November 1996, Khalil received a transit visa from the U.S. Consulate in Jerusalem for travel through the United States to Ecuador. A subsequent investigation found that Khalil had been interviewed only briefly by a consular officer, and that the officer did not require him to produce a plane ticket for Ecuador nor to demonstrate that he had funds for the trip. The officer also did not consider requiring him to catch a connecting flight in "transit without visa" status, which would have required him to stay in the airport.

Khalil appears never to have had any intention of going to Ecuador. After he cleared immigration inspection, he boarded a flight to Syracuse, New York, and remained in the United States until his arrest in July 1997. Clearly, this would not have been possible had the consular officer attempted to verify Khalil's story or simply not granted him a transit visa.

While some terrorists received inadequate interviews, others never had any contact with a consular officer. At least three of the September 11 hijackers (Abdulaziz Alomari, Salem al Hamzi, and Khalid al Midhar) obtained their visas through a system called "Visa Express" used by the American consulates in Saudi Arabia, which allows applicants to submit their applications and supporting documents through a designated travel agency. Although the applications are reviewed at the consulate and the names are run through the watch list, the applicants are never interviewed by a consular officer. Without having an in-person interview, the issuing officer cannot be sure that the person applying for the visa is actually the person named in the submitted documents and application. All varieties of deception and fraud become much more difficult to detect.

The Visa Express system was set up to make things easier for Saudi Arabian applicants and to reduce the workload of the consulate. But such a system is completely inappropriate for a country like Saudia Arabia where, as was known even prior to September 11, a large share of the population was sympathetic to bin Laden's ideology.

Give Me Your Terrorists

Inadequate or absent interviews have also rendered Section 214(b) of the Immigration and Nationality Act a much less effective tool for keeping out terrorists. Section 214(b) states that individuals who appear likely to overstay their temporary visas and try to settle permanently in the United States are not to be issued one. An applicant is supposed to demonstrate that he has a residence abroad to which he is likely to return, that his visit to the United States will be temporary, and that he has enough money to finance the visit and return trip.

Officers are trained to look for evidence of strong ties to the applicant's home country, such as family, a good job, and property, and to be skeptical of an applicant who fits the profile of someone who will overstay his visa. The criteria vary from country to country, but suspect individuals are generally young, unemployed or earning a low income, and unmarried. Individuals who apply outside of their countries of nationality should invite additional scrutiny, according to consular regulations and training manuals. Often these applicants are the ones who have difficulty establishing ties to their home country or to the country in which they now live.

Though designed to prevent illegal immigration, Section 214(b) also offers protection against the terrorist threat. Persons with families, property, and other commitments in their home countries are less likely to be part of a terrorist plot, especially one that involves suicide. Moreover, many senior members of Islamic extremist movements live outside of their own countries (often in the West) because the security services in most Muslim countries have crippled their organizations at home. Sadly, the provisions of Section 214(b) have been only weakly and sporadically enforced.

A number of the September 11 hijackers almost certainly should have been refused a temporary visa under Section 214(b). Ringleader Mohammed Atta was single, unemployed, and had lived in Germany and not his home country of Egypt for most of the 1990s. It is hard to see how he could have overcome the mandatory presumption that he would likely overstay the tourist visa he was issued. It appears that at least three other September 11 hijackers, those who provided the muscle to overpower the flight crews, should also have been denied visas under 214(b). Hijackers Mohand al Shehri, Majed Moqed, and Ahmed al Haznawi were all reportedly in their early twenties, unmarried, and had little income. The September 11 hijackers are not the only militant Islamic terrorists who should have been classified as individuals likely to overstay their visas. Mohammed Salameh, who was involved in the plot to bomb New York City landmarks, was given a tourist visa in 1988, despite the fact that he was only 19 years old, unmarried, and reportedly making $50 a month in Jordan.

By Land or By Sea

Lax border enforcement have also facilitated the entry of al Qaeda terrorists. The nation's ports of entry are the places where people traveling by land, sea, or air legally enter the United States. These entry points are staffed by immigration and customs inspectors. Of the 48 terrorists considered here, 45 of them had contact with an inspector at a port of entry.

In some instances, inspectors have succeeded in preventing terrorists from coming into the country. The Millennium plot was averted when Ahmed Ressam was stopped by an inspector at the border - the officer thought Ressam looked nervous. And Ahmad Ajaj was placed in detention when an inspector at JFK airport realized he was trying to enter the country on a fake Swedish passport - although he still took part in planning the first World Trade Center attack from his jail cell. These cases show why careful inspection at the port of entry is critical to homeland security.

While such inspections have caught a few terrorists, the main tool used for identifying terrorists is still the watch list, to which inspectors at ports of entry have access through the Integrated Border Information System administered by the Customs Service. However, the names of people entering the country are often not checked against the list because of time constraints, limited personnel, and computer problems. At the Canadian border, most people crossing through are not checked against the list.

Since individuals entering under the visa waiver program have never had their names checked by an American consulate, it is crucial to do so at the port of entry. Still, some have asked why a person with a visa, who has been cleared by a consulate, should have his name checked each time he enters the United States. But as the case of September 11 hijacker Khalid al Midhar shows, an individual can be identified as a terrorist after he receives his visa but before he enters the country. For the system to be effective, the names of all persons entering the country must be checked against the list. There is no technological impediment to checking all names at all ports of entry, though doing so would require far more resources, including computer equipment, training, and personnel.

Inadequate computer systems, staffing, and training at ports of entry have also made it difficult to record arrivals and departures from the United States. Congress did pass legislation in 1996 to create an entry-exit database. But because of INS incompetence and significant opposition from the business community, the project went nowhere. As a result, the INS does not know whether foreign visitors admitted on temporary visas actually leave the country when their visas expire. There is no mechanism for tracking land departures, and the system for tracking arrivals and departures by air, which is how most visa holders travel, is largely nonfunctioning. The current practice requires foreign visitors to fill out a two-part form with their names, passport numbers, and destinations. The opportunities for failure are enormous: Airlines often neglect to collect the forms on outbound flights or forward them to the INS; visitors may enter by air but leave by land, leaving no trace of their departure; and the information on the paper forms may be illegible or be improperly keyed into the system by the INS contractor.

Obviously, time limits on a visitor's stay in the United States are only meaningful if we can determine whether the deadline has been honored. At least 13 of the 48 terrorists from the last decade overstayed a temporary visa at some point prior to taking part in terrorist activities. Had we had a functioning entry-exit system, we could have developed policies to go after those who overstayed their visas, perhaps disrupting one or more terrorist attacks over the last 10 years. The establishment of an entry-exit system is envisioned in recently passed legislation, but it remains to be seen whether it will ever be implemented.

Terrorists have also slipped into the country illegally. Several have sneaked into the country at our sea ports. Millennium conspirators Abdelghani Meskini and Abdel Hakim Tizegha both originally entered the United States as stowaways on ships that docked at a U.S. port. Crew members of cargo ships, stowaways, and those being smuggled into the country are all potential threats. Other terrorists have entered the country from Canada. After originally coming as a stowaway, Tizegha eventually went to Canada for a time before slipping back across the northern border. Gazi Ibrahim Abu Mezer (who planned to bomb the Brooklyn subway system) also tried to sneak across the Canadian border. Tizegha was captured only after he successfully entered the country and took part in the Millennium plot. Mezer, on the other hand, was caught three times between 1996 and 1997 trying to sneak into the United States. A Palestinian, Mezer had been turned down for a student visa in 1993 at the American consulate in Jerusalem. Yet he eventually received a Canadian student visa. On his third attempt to enter the United States illegally in June 1997, the Canadian government refused to take him back. The INS then paroled him into the United States and started deportation proceedings against him. If we improve our visa processing system but fail to strengthen our land borders, we can expect more cases like these.

The fact that the INS released Mezer into the United States points to anther deficiency - a lack of detention space for holding aliens arrested for violations of immigration law or whose asylum claims are being adjudicated. While the INS does contract space from local jails, at present the agency does not have enough funding to hold most aliens who are in deportation proceedings or who have asylum claims pending. This longstanding problem has allowed terrorists to remain at large in the United States. Ramzi Yousef did not have a valid visa when he arrived at JFK airport in September of 1992, but he applied for asylum and was paroled into the United States while his claim was adjudicated.

Mir Aimal Kansi, the murderer of two CIA employees in 1993, overstayed a business visa and later applied for asylum. Instead of being detained, he was issued a work permit for a year while his asylum claim was pending. (As part of reforms implemented in 1995, the INS no longer automatically issues work permits to asylum applicants.) As detailed above, attempted New York subway bomber Gazi Ibrahim Abu Mezer was also paroled into the United States in June 1996 because of insufficient detention space. This lack of detention space effectively makes the northern border meaningless.

Homeland Security

A potential weapon in the fight against terrorism is the knowledge that many of the terrorists considered here violated America's immigration laws before taking part in terrorism. Twelve of the 48 terrorists were illegal aliens when they committed their crimes, and at least five others had lived in the country illegally at some point prior to taking part in terrorism. Moreover, at least five others had committed significant violations of immigration law prior to their terrorist acts. In addition to overstaying temporary visas and sneaking into the United States, terrorists have violated immigration laws in a number of different ways. Both Fadil Abdelgani, who took part in the plot to bomb New York City landmarks, and Khalid Abu al Dahab, who raised money and helped recruit new members for al Qaeda, engaged in fraudulent marriages to American citizens. Sheik Omar Abdel Rahman was able to obtain a green card by qualifying as a minister of religion using a false name. At least eight terrorists had held jobs for extended periods while living in the country illegally. This number includes several of those involved in the 1993 World Trade Center attack, the plot to bomb New York landmarks, and the Millennium plot.

The current immigration system has many points of weakness. It does not vigorously interview or carefully check the backgrounds of visa applicants. Nor does it enforce time limits on temporary visas. Fraudulent applications for green cards are often approved, and people in the country illegally are allowed to work, open bank accounts, and receive driver's licenses. The INS and consular officers are simply overwhelmed by the number of applicants they must process, and are stretched so thin that they cannot do their jobs. In addition, the nation's borders remain largely undefended. No system, of course, will catch every terrorist every time, but a more tightly controlled immigration system would greatly increase the chances that at least some of those involved in a large conspiracy like the September 11 attacks will be caught.

For our immigration system to be an effective part in the war against Islamic extremists, it does not have to become an antiterrorist operation. With the exception of improving the watch list, most of the problems identified above involve the mundane work of careful issuance of visas, developing a system to track the arrival and departure of foreign citizens, painstakingly verifying green-card applications and, most importantly, prosecuting those who violate the law. Failure to learn from past mistakes and to develop a better, more thorough immigration system will significantly increase the chance of another attack on American soil.

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The Center for Immigration Studies is an independent, non-partisan, non-profit research organization founded in 1985. It is the nation's only think tank devoted exclusively to research and policy analysis of the economic, social, demographic, fiscal, and other impacts of immigration on the United States.